Flame arrestor for crankcase ventilating apparatus



May 11, 1965 L. J. BINTZ 3,

FLAME ARRESTOR FOR CRANKCASE VENTILATING APPARATUS Filed Feb. 28, 1964 2Sheets-Sheet 1 'IIIII '0- g 6 INVENTOR. i Lou/.9 c]- B/NTZ BY' 20 i M 51/9214/ United States Patent 3,182,647 FLAME ARRESTOR FOR CRANKCASEVENTILATKNG APPARATUS Louis J. Bintz, Placeute, Calif, assignor to News-Thermad'or Corporation, Los Angeles, Calif a corporation of CaliforniaFiled Feb. 28, 1964, Ser. No. 348,217 17 Claims. (Cl. 123119) Thepresent invention relates to air pollution control by ventilating blowbygases from internal combustion engine crankcases and returning theseblowby gases to the air-fuel intake systems, and it relates particularlyto a novel method and apparatus employed in connection with suchcrankcase ventilating systems for preventing damage which mightotherwise occur to the engine due to backfiring in situations whenthereis gasoline in the crankcase, and for preserving normal carburetoroperation during cold start conditions when such crankcase ventilatingsystems tend to disrupt the normal fuel-air mixture required'for vehiclestarting.

Control of exhaust emissions from automotive internal combustion engineshas become a serious problem in urban areas because of the largequantities of smogforming and other harmful exhaust gas components, suchas unburned or partially burned hydrocarbons and carbon monoxide, whichare being dumped into the atmosphoto from the engines of automobiles,trucks and buses. These pollutants are discharged into the air throughthe exhaust system of the engine, and also as gases blown past thepistons in the cylinders and into the crankcase. Thesecontaminantcontaining blowby gases are then discharged from thecrankcase into the air through the oil fill cap or other crankcase venttube, such as the road draft tube usually employed with automobileengines. Such blowby gases account for a substantial portion of the airpollutants from internal combustion engines.

Several systems are presently in use for controlling these blowbyexhaust gases, the systems usually involving con duit means connectingthe crankcase with the intake manifold to utilize the vacuum conditionin the intake manifold to draw the blowby exhaust gases out of thecrankcase and into the vehicle intake system, so that the combustiblesin the blowby gases, which are the principal harmful ingredients, willagain be subjected to the engine combustion cycle. A typical crankcaseventilating system of this general type will provide the conduit betweenthe valve rocker arm cover, which is accessible at the top of the engineand which communicates with the crankcase, and the intake manifold,which is also readily accessible. Some valve means is normally employedin the conduit so as to restrict or control the volume of gas flow fromthe crankcase to the intake manifold, in an attempt to prevent theapplication of too much vacuum to the crankcase, which would tend todraw air in through the crankcase seals, and at the same time to preventthe introduction of so much air to the engine intake system from thecrankcase as to disrupt carburetion.

One such internal combustion engine crankcase ventilating system whichhas been found satisfactory is disclosed in copending application SerialNo. 321,556, filed November 5, 1963, entitled Apparatus for VentilatingInternal Combustion Engine Crankcase, which is a joint application ofthe present applicant and Kenneth E. Rawald. Said copending applicationSerial No. 321,556, employs a flow regulator valve in the conduit fromthe crankcase to the intake manifold which is responsive both to intakemanifold vacuum and to the vacuum or pressure condition within thecrankcase so as to meter the flow from the crankcase to the intakemanifold generally "ice in accordance with the amount of the blowbygases which are accumulating in the crankcase under various engineoperating conditions. Although the present invention may be employed inconnection with any crankcase ventilating system of the type embodying aconduit from the crankcase to the engine intake manifold, I have shownand described the present invention in association with a system havinga flow regulator valve of the type disclosed in said copendingapplication Serial No. 321,556, because when the invention is used incombination with such system the conduit from the crankcase to theintake mani fold is properly apertured for substantially all operationalconditions that are likely to be encountered.

There are several problems in connection with crankcase ventilatingsystems which it is the purpose of the. present invention to cure. Oneproblem is that under certain engine. operating conditions, such as whencranking the engine during cold starts, raw gasoline or gasoline fumesare likely to accumulate in the crankcase, and if the engine shouldbackfire, i.e. if the mixture should ignite in the intake manifold andcarburetor, with the added crankcase ventilating conduit the backfireflame will pass through the conduit and a damaging explosion may occurin the crankcase. Another problem which it is a purpose of the inventionto cure is that when the engine is being started, particularly in coldwheather, air is drawn into the intake manifold from the crankcasethrough the communicating conduit of the ventilating system, whichbreaks the vacuum in the manifold and disturbs the fuel-air mixture,thus making starting more diificult.

in view of these and other problems, it is an object of the presentinvention to provide a novel method and apparatus employed in connectionwith a crankcase ventilating system of the type providing communicationbetween the crankcase and the engine intake manifold, which willpositively block the passage of backfire flames from the intake manifoldthrough the crankcase ventilating conduit so that any gasoline orgasoline fumes in the crankcase cannot be ignited by backfiring. I

Another object-of the present invention is to provide a method andapparatus of the characterdescribed for use in a crankcase ventilatingsystem, wherein the ventilating conduit from the crankcase to the intakemanifold is effectively closed during cold start conditions so that theintake fuel-air mixture will not be disturbed by air being sucked infrom the crankcase, yet which does not interfere with the normalventilating operation of the system under other engine operatingconditions.

A more specific object of the present invention is to provide novelvalve apparatus in a crankcase ventilating system which is normally opento permit the free flow of blowby exhaust gases from the crankcase tothe intake manifold, yet which automatically closes in response tobackfire pressure in the intake system to protect against crankcaseexplosions, and which will also automatically be held closed during coldstart conditions to prevent disturbance of the normal fuel-air mixtureat that time.

Further objects and advantages of the present invention will appearduring the course of the following part of the specification, whereinthe details of construction and mode of operation of several embodimentsare described with reference to the accompanying drawings, inwhich:

FIGURE 1 is an elevation view showing crankcase ventilating apparatusembodying the present invention in a typical installation, with anassociated internal combustion engine graphically represented inphantom.

FIGURE 2 is an axial section through the How regulator valve of thesystem shown in FIGURE 1, with one embodiment of the flame arrestor ofthe present invention disposed in the same case as the flow regulator,the

3 elements of the flow regulator and flame arrestor being shown inpositions they would assume during engine operation.

FIGURE 3 is a cross-sectional view taken on the line 3-3 in FIGURE 2,illustrating internal details of construction'of the flame arrestor.

. FIGURE 4 is an exploded view illustrating the fire check plate andseal diaphragm components of the embodiment of the invention shown inFIGURES 2 and 3.

FIGURE 5 is an axial sectional view similar to FIG- URE 2, but with theelements of both the flow regulator and the flame arrestor shown intheir positions of repose, as they would be with associated internalcombustion engine inoperative.

FIGURE 6 is an axial section generally similar to FIGURE 2, butillustrating an alternative form of the flame arrestor associated withthe flow regulator.

FIGURE 7 is a cross-sectional view taken on the line 7-7 of FIGURE 6showing further details of this alternative form of the invention.

FIGURE 8 is an exploded view illustrating the spacer and valve elementparts of the alternative form of the invention shown in FIGURES 6 and 7.

Referring to the drawings, and at first to FIGURE 1 thereof, thecrankcase ventilating apparatus in which the present invention isemployed is designated generally by the numeral 10, and includes a flowregulator 12 having an inlet conduit 14 which is connected to enginerocker arm cover 16. The blowby exhaust gases accumulating in the enginecrankcase 18 flows through the engine along the path shown by the arrowsto the space within rocker arm cover 16, and thence into conduit 14. Theflow regulator valve 12 has an output conduit 20, in this case aflexible hose, which is connected to a suitable fitting on the intakemanifold 22 of the engine. The flame arrestor 24- of the presentinvention has been shown embodied within an extension of the housing forthe flow regulator valve 12, although it is to be understood that thefiame arrestor may be disposed at any place in the flow conduit meansfrom the crankcase 18 to the intake manifold 22. Preferably, the flamearrestor will be disposed in the conduit means on the intake manifoldside of the flow regulator valve 12 so as to provide protection for theflow regulator valve 12.

' FIGURES 2 to 5 illustrate the details of construction of the flowregulator valve 12 and the associated flame arrestor 24. Although theflame arrestor 24 may be employed in connection with any crankcaseventilating system which provides connection between the crankcase andthe intake manifold, the particular system with which flame arrestor 24has been shown in the drawings cooperates with the flame arrestor toprovide substantially the desired rate of gas flow through the systemunder virtually all conditions of engine operation, which is unique forthis combination of the particular flow regulator valve and flamearrestor shown.

Referring now particularly to FIGURES 2 to 5, the flow regulator valve12 has a casing 26 which includes a body 28 and a cap 30 peripherallyclamped to body 28. Formed as a part of the body 28 is a valve outletnozzle 32 having an inner end opening 34 which provides the valve seat.A flexible diaphragm 36 is peripherally clamped between the body 28 andthe cap 30 so as to divide the space within the casing 26 into a pair ofchambers 37 and 38, the chamber 37 being on the body side of thediaphragm and the chamber 38 being on the cap side of the diaphragm.

A diaphragm plate 39 seats against diaphragm 36, and has a central bulge40 which is adapted to seat in the nozzle opening 34 in the closedposition of the flow regulator valve. The bulge 40 has a bleed slot 42therein to permit a small amount of gas flow through the valve even insuch closed position. Valve spring 44 is engaged at one end against thebody 28, being positioned over valve o let nozzle 32, and is engaged atits other end against the diaphragm plate 39, the spring 44 holdingplate 39 against diaphragm 36 and biasing the diaphragm and plate awayfrom the nozzle opening 34 so that the position of repose of the valveis the open position. The spring 44 engages the diaphragm plateproximate the annular juncture between the bulge 40 and the fiat part ofthe plate, so that the spring 44 tends to center the bulge 40 withrespect to the nozzle opening 34. Otherwise, the plate 39 isfree-floatin g with respect to diaphragm 36, so that the plate bulge 40has a self-centering action as it moves into the closed position in thenozzle opening 34. By this means, proper closure of the flow regulatorvalve is assured despite irregularities which might occur frommanufacturing tolerances or some physical damage to the valve, thusassuring relatively accurate control of the exhaust gas flow through thevalve.

The conduit 14 which is connected to the engine rocker arm covercommunicates with valve chamber 37 through valve inlet port 46.

An atmosphere vent hole 48 is provided in cap 30 so that chamber 38 isan atmospheric pressure.

The spring 44 is a relatively light spring which is adapted to keep thevalve nozzle open for outlet gas pressures (i.e. intake manifoldnegative pressures) equal to and more positive than a pie-selectedoutlet gas pressure. Thus, the spring has a force equal to the desiredvalve opening pressure times the effective diaphragm plate area oppositethe valve nozzle opening 34.

The pre-selected pressure to be maintained at the regulator valve inletport 46, and hence in the crankcase chamber itself, is a negativepressure sufficient to draw all of the blowby gases out of thecrankcase, yet which is not so negative that too much air will be drawnin through the crankcase, or to cause a tendency to draw dirt in throughthe crankcase seals. While there is a sufficiently strong vacuum in theintake manifold to draw such blowby gases from the crankcase if a simpleopen tube connection is made from the manifold to the crankcase, such aprocedure is not practical because the high manifold vacuums at lowspeeds are too high to be transmitted directly to the crankcase. Theflow regulator valve 12 which is shown in FIGURES 2 and 5, and which hasthe same essential functional elements as that shown in said copendingapplication Serial No. 321,556, provides controlled flow of gases fromthe crankcase to the intake manifold which closely matches the flowvolume of blowby gases into the manifold.

The operation of the flow regulator 12 is generally as follows: Theintake manifold vacuums are transmitted to the regulator valve throughthe valve nozzle 32 with its open end 34 inside the chamber 37, thesenegative pressures varying from about 20 inches of mercury to less thanabout 1 inch of mercury. These intake manifold negative pressures actdirectly upon the central bulge 4i) of the diaphragm plate, on an areaabout equal to the cross-sectional area of the nozzle opening 34,tending to pull the diaphragm and diaphragm plate against the open endof the valve nozzle to shut it. The spring 44 functions to push thediaphragm plate and diaphragm away from the open end of the valve nozzlewhen the blowby rate increases so that these gases may pass into thenozzle.

The spring 44 forces the diaphragm plate and diaphragm away from thevalve opening when the intake manifold vacuum tending to close the valvebecomes weaker than the force of the spring tending to open the valve.The spring is selected so as to have a valve opening force equal to theforce of a selectedintake manifold negative pressure, as for exampleabout 16 or 15 inches of mercury. The diaphragm will, therefore, bedrawn against the open end of the valve nozzle at high manifold vacuums,as for example 20 to 16 inches of mercury. The blowby flow rate at thesehigh manifold vacuums is low and the small amountof blowby gases aredrawn into the valve nozzle opening through various leakage points, orby the limited access port formed by the bleed slot 42. When the intakemanifold vacuums become weaker, or more positive, as for example 16 orinches negative pressure, the force of the spring pushes the diaphragmplate and diaphragm away from the valve nozzle opening allowing a largergas passage to the valve nozzle. The blowby gas flow rate is beginningto increase at these manifold pressures, and gases are able to easilyflow into the valve nozzle opening because of the larger access area.The now increasingly absolute, or more positive, pressures in thecrankcase provided a lifting force against the diaphragm tending to pushthe diaphragm and diaphragm plate further away from the valve nozzleopening, making an even greater access passage.

There is always a negative pressure in the crankcase. At high intakemanifold vacuums, the direct manifold action drawing the diaphragm plateand diaphragm down against the nozzle will be assisted by the weakernegative pressure in the crankcase, which will also tend to keep thevalve shut by pulling on the larger area of the diaphragm which isradially outwardly disposed relative to the nozzle. However, as theintake manifold vacuum becomes weaker, the crankcase vacuumv likewisebecomes weaker; and once the spring has opened the valve the crankcasevacuums will become increasingly weaker, tending to allow the spring topush the diaphragm even further away. In this regard, it is to be notedthat the terms used herein stating that negative pressures or vacuumsbecome weaker, or more absolute, or more positive, means that thepressure is approaching atmospheric pressure.

The crankcase pressures exert only a small diaphragm lifting pressure,but they exert their force on a much larger area of the diaphragm thanthe intake manifold pressures.

These crankcase pressures exert their force over an annular portion ofthe diaphragm extending from the diaphragm flexure or bending line intoabout the circular area of the bulge of the diaphragm plate adjacent theopen end of the nozzle. The diaphragm'lifting action of the increasinglymore absolute crankcase pressures on the larger area of the diaphragmincreasingly releases the spring biasing force on the diaphragm plateand the spring pushes the diaphragm plate away from the valve nozzleproviding a maximum size passage for unrestricted flow into the valvenozzle, and this condition is the condition of engine operation whichprovides high blowby flow rates.

As the engine speed or workload increases, the blowby flow rate willincrease, and at the same time the intake manifold vacuum will decrease.Conversely, as the engine speed or workload decreases, the blowby flowrate decreases, while at the same time the intake manifold vacuum tendsto increase. As seen from the above description of the operation of howregulator valve 12, the valve tends to be closed by increased manifoldvacuums, and tends to be opened by increased flow rates of blowby gasesinto the crankcase, which tends to increase crankcase pressure, wherebythe combined effects tend to modulate the valve so as to accommodate theflow of blowby gases at various engine operating conditions withoutapplying too much vacuum to the crankcase, and without providing toomuch air from the crankcase to the intake manifold so as to interferewith proper carburetion.

FIGURE 2 illustrates the flow regulator valve 12 in a slightly openposition, which would correspond to a moderate engine speed or workload,while FIGURE 5 illustrates the regulator valve in its completely openposition, or position or repose, which is the position of the valve whenthe engine is not operating. It will be apparent that when the engine isbeing cranked for starting, at which time it is revolving at only about50 to 150 r.p.m., the intake manifold vacuum will not be sufiicient tosubstantially close the valve 12, and it will be at or near its positionof repose as shown in FEGURES, during which condition the how regulatorvalve 12 provides practical- 6 1y a wide open communication between thecrankcase and the intake manifold. However, such wide open communicationbetween the crankcase and intake manifold destroys the eifectiveness ofthe choke valve for cold start conditions, breaking the intake manifoldvacuum, and provides added air so that the mixture is too lean forproper starting. Thus, it is important for proper cold starting toprovide additional flow control means in the conduit from the crankcaseto the intake manifold which will be substantially closed during coldstart conditions to compensate for the substantially wide open conditionof the how regulator valve 12, and this additional means is provided bythe flame arrestor of the present invention.

Another circumstance in which it is important to close the conduitbetween the crankcase and the intake manifold is whenever there is abackfire (i.e. inadvertent ignition of the fuel-air mixture in thecarburetor-intake manifold system). This latter circumstance is mostdangerous whenever there is a tendency for raw gasoline or gasolinefumes to concentrate in the crankcase, which tends to occur during coldstarting conditions and also frequently when the engine has beenoperating, is turned off, and is again turned on while it is still hot.The present invention automatically blocks the conduit between thecrankcase and intake manifold whenever there is such a backfire,regardless of how open the regulator valve 12 might be at thatparticular engine operating condition.

The body 23 of the casing for the flow regulator valve is provided withan emension St) for housing the flame arrestor. Extension '54) has anannular shoulder 52, beyond which the extension terminates in an annularlip 54.

Seated against the shoulder 52 and disposed within lip '54 is a tirecheck plate 56, which may be composed of sheet metal or other suitablematerial, and which has a plurality of apertures 53 therethrough.-Although three of the apertures 58 can be employed, preferably thereare four apertures 58 provided, and these are regularly spaced aboutplate 56 at approximately the same radial distance from the center ofthe plate. The =fire check plate 56 is preferably bowed or dishedsomewhat in the downstream direction for a purpose to be hereinafterdescribed.

Immediately downstream of the fire check plate 56 is fire check sealdiaphragm 69 comprising a relatively thin, flat sheet of materialwhichjis resilient and flexible and which has good memory characteristics,preferably but not necessarily an elastomer material; Diaphragm 6t hassubstantially the same diameter as the check plate'56, and is providedwith a plurality of slits 62, the number of which depends upon thenumber ofapertures S8 in the fire check plate 56. Thus, in theembodiment shown in the drawings, a pair of the slits 62am provided,cross.- ing each other at right angles, with small circular holes 64provided at the ends of the slits to prevent tearing. The slits 62 thusprovide a plurality of generally .triangular flaps 66, these being fourin number. in the embodiment shown in the drawings. The seal diaphragm60 is rotationally oriented with respect to fire check plate 56 so thateach of the flaps 66 registers with a respective aperture 58,.and theslits. 62 extend between the apertures 58. In this manner, when thesealdiaphragm 60 is in its position of repose, as shown in FIGURE 5, theflaps 66 will completely close oil the respective apertures 58. Sincethe seal diaphragm 69 is a fiat sheet of resilient material in itscompletely relaxed position, the bowed or dished shape of fire checkplate so will apply a downstream deflection to each of the four flaps 66of diaphragm d d as shown in FIGURE .5, which results in each of theflaps 66 being biased to its closedposition over its respective aperture58 due to the resiliency of the diaphragm material.

The flame arrestor structure of the embodiment shown in FIGURES 2 to 5is completed by a closure 68 which has an outwardly directed annularflange 7t) that fitsinto the body extension lip 54, the lip 5 3 beingturned inwardly to compress the flange '76 against the periphery ofdiaphragm 60 so as to peripherally seal the diaphragm and fire checkplate within the extension 50. Closure 68 also has a tubular nipple 72which extends downstream and is adapted to provide a hose connection forthe hose 20 shown in FIGURE 1 leading to the intake manifold. Theclosure 63 may also include a shoulder 73 facing upstream which limitsthe amount of flexing of the diaphragm flaps 66 to minimize wear of theflaps.

Under normal engine operating conditions the diaphragm flaps 66 arehighly flexible, and they will not substantially impede the free flow ofblowby gases passing from the crankcase and through the flow regulatorvalve 12 to the intake manifold. The flaps 66 will merely flex in adownstream direction as shown in FIGURE 2 so that the blowby exhaustgases will flow through the apertures 58 without substantial resistancefrom the flaps 66.

However, in the event of a backfire, there will be a sudden increase ofintake manifold pressure with respect to the pressure in the crankcase,causing a reverse rush of gases, which will instantaneously close theflaps 66 over the respective apertures 58 and prevent the flame front ofthe backfire from passing through the flame arrestor 24, and hence backthrough the flow regulator valve 12 and into the crankcase, where rawgasoline or gasoline fumes might be ignited. At this time the fire checkplate functions as a valve seat against which the diaphragm flaps rest.As the backfire subsides, and the normal direction of flow is resumed asindicated by the arrows in FIGURE 2, the flaps 66 will againautomatically open.

Control of the flow of gases from the crankcase to the intake manifoldduring cold start conditions is achieved in the flame arrestor 24 byemploying a resilient flexible material in the seal diaphragm 60 whichbecomes stilt or substantially rigid when it is cold, so that when theengine is cold the diaphragm flaps 66 will be fixed in their closedpositions as shown in FIGURE 5, thus preventing any substantial flow ofair or other gases from the crankcase to the intake manifold. It isdesirable that the material of diaphragm 60 stiffen or freeze up attemperatures below about 70 F., and it is particularly important atsub-zero temperatures.

Although any sufliciently durable material having these characteristicsmay be employed in the present invention, one such material which theapplicant has found to be satisfactory in operation is the syntheticrubber product Viton produced by Du Pont, which has the characteristicof stiffening and losing its flexibility at about 20 F. and lower, butwhich is quite flexible at higher temperatures.

When the engine is turned off after operation, it will be hot and thediaphragm 60 will be flexible, so that the diaphragm will automaticallymove to its closed position as shown in FIGURE 5. Thus, this is theposition in which the diaphragm will stiffen when the engine becomescold. Accordingly, when the engine is cold the diaphragm flaps 66 willremain substantially closed as shown in FIGURE and there will be nosubstantial flow of air or other gaseous materials from the crankcaseinto the intake manifold to in any way disturb the rather sensitivecarburetion balance under cold starting conditions. However, long beforethe engine reaches normal operating temperatures of about 200 F. thediaphragm 60 will become highly flexible and the flaps 66 will bepermitted to flex to their open positions as shown in FIGURE 2, toaccommodate the passage of blowby exhaust gases from the crankcase tothe intake manifold.

Referring now to FIGURES 6, 7 and 8, these FIG- URES illustrate analternative flame arrestor 74 which utilizes a substantially rigid,spring-biased flame arrestor valve element instead of elastomcr sealdiaphragm 60 of the form of the invention shown in FIGURES 2 to 5.

The flame arrestor 74 is adapted to be mounted in the flow regulatorvalve body extension 58, and includes a spacer 76 supported in the lip54 against shoulder 52. Spacer 76 is in the form of a spider havingradially outwardly projecting legs 78 which are engaged against theshoulder 52, and includes a central tubular guide ring 80 extending inthe upstream direction from the legs 78.

The closure 82 is similar in construction to closure 68, including anoutwardly directed annular flange 84 which seats against the spacer legs78 and is secured there in substantially sealed relationship to thehousing by the lip 54 of the housing extension being turned inwardly.The closure 82 includes nipple 86 to provide a connection for the hose20 shown in FIGURE 1.

The flame arrestor 74 includes a valve element 35 comprising a generallyflat disc 90 having peripheral tongues 92 which extend in the downstreamdirection at right angles to the disc. The flame arrestor valve element88 is normally biased by a spring 94 toward its closed position againsta valve seat $6 in the housing at the downstream end of nozzle 32. Thespring 94 is engaged at one end about the tubular guide ring 86 and atits other end against the disc 90 of flame arrestor valve element 88,the valve element being held in alignment with the nozzle 32 byengagement of spring 94 between the tongues '52.

The spring 94 is a relatively light spring, so that the flame arrestorvalve clement does not substantially impede the free flow of blowbyexhaust gases from the crankcase to the intake manifold during normalengine operating conditions. However, in the event of a backfire, thereversed pressure differential will instantaneously move the flamearrestor valve element against the seat 96 to prevent passage of theflame front to the crankcase.

The flame arrestor embodiment '74 has a cold start operation which issomewhat similar to that of the embodiment 24 shown in FIGURES 2 to 5.Several factors contribute to this. One factor is that the enginestarter will crank the engine at from about 50 to about r.p.n1., whichproduces only a relatively small amount of intake manifold vacuum. Bychoosing a spring 94 of the proper strength, the spring 94 will tend tohold valve element 88 in a substantially closed position when the engineis rotating at this very low starting speed, but as soon as the engineassumes a condition of normal operation, as for example idling (at 500r.p. m. or more), or other operating condition, the pressuredifferential on opposite sides of the flame arrestor valve element 88will cause the element 88 to open as shown in FIGURE 6.

Another factor contributing to the cold start operation of the flamearrestor embodiment 74 is the fact that a film of engine oil from thecrankcase will become deposited on the flame arrestor valve element 88and its valve seat 96, and when the engine is cold and flame arrestorvalve element 88 is in its position of repose biased against its valveseat 96, the cold and hence viscous oil will cause the valve element 88to stick against seat 96. This action is enhanced by providing flatsurface engagement between the valve element disc 90 and the generallyflat seat 96, which provides a substantial area of the viscous oil filmfor causing the valve element 83 to adhere to the valve seat 6. When theengine warms up, this oil will likewise warm up and become more fluid,thereby releasing the valve element 88 from seat 96.

While the instant invention has been shown and described herein in whatare conceived to be the most practical and preferred embodiments, it isrecognized that departures may be made therefrom within the scope of theinvention, which is therefore not to be limited to the details disclosedherein, but is to be accorded the full scope of the claims.

What I claim is:

1. A flame arrestor for use in a crankcase ventilating conduit extendingbetween the crankcase and the intake manifold of an internal combustionengine, said flame arrestor comprising a housing adapted to be disposedin said conduit, said housing having a passage therethrough forming apart of said conduit, a valve seat proximate said passage in saidhousing facing-downstream for the normal direction of gas flow from thecrankcase to the intake manifold, a valve element in said housing on thedownstream side of said seat, said valve element being held by the flowof gases in an open position spaced downstream of said valve seat duringnormal engine operation when the intake manifold is at a lower pressurethan the crankcase to permit the substantially unimpeded flow of blowbyexhaust gases from the crankcase through the conduit to the intakemanifold, and the valve element being movable to a closed positionagainst said seat to block the flame front from the crankcase upon apressure reversal resulting from backfiring in the engine fuel intakesystem, and means lightly biasing said valve element toward said seat,whereby the position of repose of said element when the engine isinoperative and there is no pressure differential between'the crankcaseand the intake manifold is the closed position of the element againstthe seat, said biasing means exerting a biasing force which issuiiiciently light so that during normal engine operation said elementwill not substantially impede the flow of blowby exhaust gases from thecrankcase to the intake manifold.

' 2. A flame arrestor as defined in claim 1, wherein said biasing meanshas the physical characteristic that it stiflens and becomessubstantially rigid at low temperatures corresponding to cold startengine temperatures, whereby under cold engine starting conditions saidbiasing means will be substantially rigid with said valve element in itssaid closed position so as to substantially block the flow of gases fromthe crankcase to the intake manifold so that such flow will not upsetcarburetion at that time.

3. Apparatus as defined in claim 1, wherein said valve element comprisesa sheet of resilient material supported in said housing with a portionthereof movable between said open and closed positions, said sheet beingso arranged that the resiliency thereof provides said biasing means.

4. Apparatus as defined in claim 1, wherein said valve element is asubstantially rigid member, said biasing means comprising a springsupported in the housing and engaged against the valve element.

5. Apparatus as defined in claim 4, wherein said valve element and seathave opposed, substantially flat surfaces which mate in said closedposition of the valve element so that at low temperatures oil entrappedbetween said surfaces will be highly viscous and will cause i saidsurfaces to adhere together, whereby under cold engine startingconditions said valve element will substantially block the flow of gasesfrom the crankcase to the intake manifold so that such flow will notupset carburetion at that time.

6. A flame arrestor for use in a crankcase ventilating conduit extendingbetween the crankcase and the intake manifold of an internal combustionengine, said flame arrestor comprising a housing adapted to be disposedin said conduit, said housing have a passage therethrough forming a partof said conduit, a valve seat proximate said passage in said housingfacing downstream for the normal direction of gas flow from thecrankcase to the intake manifold, and a valve element comprising a sheetof resilient material supported in said housing with a portion thereofdisposed on the downstream side of said seat and movable between an openposition spaced from said seat where it is held by the flow of gasesduring normal engine operation when the intake manifold is at a lowerpressure than the crankcase to permit the substantially unimpeded flowof blowby exhaust gases from the crankcase through the conduit to theintake manifold, and a closed position against said seat to block theflame front from the crankcase upon a pressure reversal resulting frombackfiring in the engine fuel intake system, said sheet of resilientmaterial being so arranged that its resiliency biases said portionthereof toward said seat,-whereby the position of repose thereof whenthe engine is inoperative and there is not pressure differential betweenthe crankcase and the intake manifold is the closed position of saidportion of the sheet of resilient material.

7. Aflame arrestor as defined in claim 6, wherein said resilientmaterial has the physical characteristic that it stiffens and becomessubstantially rigid at low temperatures corresponding to cold startengine temperatures, whereby under cold engine starting conditions saidportion of the resilient sheet will be substantially rigid in its saidclosed position so as to substantially block the flow of gases from thecrankcase to the intake manifold so that such flow will not upsetcarburetion at that time.

8. A flame arrestor for use in a crankcase ventilating conduit extendingbetween the crankcase and the intake manifold of an internal combustionengine, said flame arrestor comprising a housing adapted to be disposedin said conduit, said housing having a passage therethrough forming apart of said conduit, a fire check plate supported in said housing so asto extend across said passage and having a plurality of gas flowapertures therethrough, and a resilient diaphragm supported in saidhousing on the side of said platewhich is downstream for the normaldirection of gas flow from the crankcase to the intake manifold, saiddiaphragm being slit to provide a plurality of flap portions which areflexible between open positions spaced from said plate where they areheld by the flow of gases during normal; engine operation when theintake manifold is at a lower pressure than said crankcase to permit thesubstantially unimpeded flow of blowby exhaust gases from the crankcasethrough the conduit and said apertures to the intake manifold, andclosed positions seated against said plate in covering relationship overthe respective said apertures to block the flame front from thecrankcase upon a pressure reversal resulting from backfiring in theengine fuel intake system, said plate and diaphragm being so arrangedthat said flap portions are biased toward their said closed positions bythe resiliency of the diaphragm material.

9. A flame arrestor as defined in claim 8, wherein said plate anddiaphragm are generally disc-shaped, said apertures being at least threein number and being substantially regularly spaced about said plate atsubstantially the same radial distance from the center of the plate, andthe diaphragm being slit radially outwardly from substantially thecenter thereof so that flap portions are generally triangular withapexes at substantially the center of the diaphragm.

10. A flame arrestor as defined in claim 9, wherein said diaphragm issubstantially flat in its unflexed condition, and is held against saidplate at its periphery, and wherein said plate is bowed toward thediaphragm so that said diaphragm flap portions are flexed in adownstream direction in their positions of repose against said plate,whereby said flap portions are biased against the plate.

11. A flame arrestor as defined in claim 8, wherein said resilientdiaphragm has the physical characteristic that it stiffens and becomessubstantially rigid at low temperatures corresponding to cold startengine temperatures, whereby under cold engine starting conditions saidflap portions of the diaphragm will be substantially rigid in their saidclosed positions so as to substantially block the flow of gases throughsaid apertures and hence from the crankcase to the intake manifold sothat such flow will not upset carburetion at that time.

12. Apparatus for use in a crankcase ventilating conduit extendingbetween the crankcase and the intake manifold of an internal combustionengine comprising: a flow regulator comprising a casing, a flexiblediaphragm within the casing dividing into a first chamber and a secondchamber, said first chamber having a gas inlet and a i i r a gas outletadapted to be connected into said conduit so that gases flowingdownstream through said conduit for the normal direction of gas flowfrom the crankcase to the intake manifold will flow through said casingfrom the inlet to the outlet, a valve nozzle inside the first chamber,one end of the nozzle communicating with the gas outlet, the other endof the nozzle terminating in an open end adjacent said diaphragm, theopen end of the nozzle being at least partially blocked to the passageof gases therethrough by the diaphragm when the diaphragm is drawn tothe open end of the nozzle by intake manifold negative pressures in thenozzle, and a spring supported in the casing biasing the diaphragm awayfrom the nozzle to keep open said open end of the nozzle for outlet gaspressures equal to and more positive than a pre-selected gas pressure;and a flame arrestor comprising a housing adapted to be disposed in saidconduit, said housing having a passage therethrough forming a part ofsaid conduit, a valve seat proximate said passage in said housing facingdownstream, and a valve element in said housing on the downstream sideof said seat, said valve element being held by the flow of gases in anopen position spaced downstream of said valve seat during normal engineoperation when the intake manifold is at a lower pressure than thecrankcase so that the valve element will not substantially interferewith control of the flow of blowby gases by the diaphragm, and the valveelement being movable to a closed position against said seat to blockthe flame front from the crankcase upon a pressure reversal resultingfrom 'backfiring in the engine fuel intake system.

13. Apparatus as defined in claim 12, wherein said flame arrestor is onthe downstream side of said flow regulator.

14. Apparatus as defined in claim 13, wherein said flame arrestorhousing comprises an extension of said flow regulator casing.

15. Apparatus as defined in claim 12, which includes means lightlybiasing said valve element toward said seat, whereby the position ofrepose of said element when the engine is inoperative and there is nopressure differential between the crankcase and the intake manifold isthe closed position of the element against the seat, said biasing meansexerting a biasing force which is sufficiently light so that duringnormal engine operation said element will not substantially impede theflow of blowby exhaust gases from the crankcase to the intake manifold.

16. A flame arrestor as defined in claim 15, wherein said biasing meanshas the physical characteristic that it stifiens and becomessubstantially rigid at low temperatures corresponding to cold startengine temperatures, whereby under cold engine starting conditions saidbiasing means will be substantially rigid with said valve element in itssaid closed position so as to substantially block the flow of gases fromthe crankcase to the intake manifold so that such fiow will not upsetcarburetion at that time.

17. Apparatus as defined in claim 16, wherein said valve elementcomprises a sheet of resilient material supported in said housing With aportion thereof movable between said open and closed positions, saidsheet being so arranged that the resiliency thereof provides saidbiasing means.

References Cited by the Examiner UNITED STATES PATENTS 3,088,447 5/63Henderson 123--119 KARL J. ALBRECHT, Primary Examiner.

1. A FLAME ARRESTOR FOR USE IN A CRANKCASE VENTILATING CONDUIT EXTENDINGBETWEEN THE CRANKCASE AND THE INTAKE MANIFOLD OF AN INTERNAL COMBUSTIONENGINE, SAID FLAME ARRESTOR COMPRISING A HOUSING ADAPTED TO BE DISPOSEDIN SAID CONDUIT, SAID HOUSING HAVING A PASSAGE THERETHROUGH FORMING APART OF SAID CONDUIT, A VALVE SEAT PROXIMATE SAID PASSAGE IN SAIDHOUSING FACING DOWNSTREAM FOR THE NORMAL DIRECTION OF GAS FLOW FROM THECRANKCASE TO THE INTAKE MANIFOLD, A VALVE ELEMENT IN SAID HOUSING ON THEDOWNSTREAM SIDE BY SAID SEAT, SAID VALVE ELEMENT BEING HELD BY THE FLOWOF GASES IN AN OPEN POSITION SPACED DOWNSTREAM OF SAID VALVE SEAT DURINGNORMAL ENGINE OPERATION WHEN THE INTAKE MANIFOLD IS AT A LOWER PRESSURETHAN THE CRANKCASE TO PERMIT THE SUBSTANTIALLY UNIMPEDED FLOW OF BLOWBYEXHAUST GASES FROM THE CRANKCASE THROUGH THE CONDUIT TO INTAKE MANIFOLD,AND THE VALVE ELEMENT BEING MOVABLE TO A CLOSED POSITION AGAINST SAIDSEAT TO BLOCK THE FLAME FRONT FROM THE CRANKCASE UPON A PRESSUREREVERSAL RESULTING FROM BACKFIRING IN THE ENGINE FUEL INTAKE SYSTEM, ANDMEANS LIGHTLY BIASING SAID VALVE ELEMENT TOWARD SAID SEAT, WHEREBY THEPOSITION OF REPOSE OF SAID ELEMENT WHEN THE ENGINE IS INOPERATIVE ANDTHERE IS NO PRESSURE DIFFERENTIAL BETWEEN THE CRANKCASE AND THE INTAKEMANIFOLD IS THE CLOSED POSITION OF THE ELEMENT AGAINST THE SEAT, SAIDBIASING MEANS EXERTING A BIASING FORCE WHICH IS SUFFICIENTLY LIGHT SOTHAT DURING NORMAL ENGINE OPERATION SAID ELEMENT WILL NOT BESUBSTANTIALLY IMPEDE THE FLOW OF BLOWBY EXHAUST GASES FROM THE CRANKCASETO THE INTAKE MANIFOLD.